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91.
92.
某些酸性三苯甲烷染料与阳离子表面活性剂相互作用的共振瑞利散射光谱及其分析应用 总被引:20,自引:1,他引:19
共振瑞利散射(RRS)法因其具有高灵敏度、简易性和较好的选择性等特点而引起了人们广泛的兴趣和关注.近年来的研究表明,RRS法也可用于研究阳离子表面活性剂(CS)与染料的相互作用以及测定痕量阳离子表面活性剂[1,2].本文研究了溴酚蓝、溴甲酚绿和溴百里香酚蓝等酸性三苯甲烷染料与氯化十四烷基二甲基苄基铵、溴化十六烷基吡啶盐和溴化十六烷基三甲铵等阳离子表面活性剂的反应.结果发现,当两者结合形成离子缔合物后,虽仅引起吸收光谱的微小变化,却能导致RRS强度的显著增强,并产生了新的RRS光谱,且在一定范围内RRS强度与阳离子表面活性剂的浓度成正比.对不同的阳离子表面活性剂,检出限在3.1~9.8 ng mL之间且具有较好的选择性和较高的稳定性. 相似文献
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Distillation was re‐evaluated for the formation of artifacts arising from increasing naturally occurring mercury(II) concentrations, as opposed to previous identification of artifacts by spiking standard mercury(II) into samples. Naturally occurring mercury(II) concentrations lower than 2 µg g?1 were found not to affect methylmercury (MeHg) results. However, when the natural concentrations of mercury(II) were greater than 2 µg g?1, in contrast to standard mercury(II) spiked in samples, the MeHg concentrations measured were found to decrease (not increase) with increasing naturally occurring mercury(II) concentrations. This indicated that standard mercury(II) spiked in samples behaved differently from naturally occurring mercury(II) in the formation of MeHg artifacts during distillation. As a result, spiking standard mercury(II) into samples to identify the formation of MeHg artifacts is not adequate. It is difficult to explain why high naturally occurring mercury(II) suppresses MeHg measurements during distillation. In comparison with HNO3 leaching/solvent extraction (and other existing techniques), distillation was found to generate results comparable for samples containing less than 2 µg g?1 mercury(II). The HNO3 leaching/solvent extraction showed significant advantages over other procedures, as this technique generated the highest recoveries with good precision for all samples analyzed, and the results were found to be independent of mercury(II) concentrations for both naturally occurring and spiked standard mercury(II). Thus, except for samples from high mercury‐contaminated fields, distillation is still a good choice. Both the positive bias (possibly caused by artifact formation of MeHg) and the negative bias (due to incomplete leaching, back‐adsorption, and/or decomposition of MeHg) were investigated. Geologically, physically, and chemically different samples were used for the investigation. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
96.
J. H. Petropoulos K. G. Papadokostaki S. G. Amarantos 《Journal of Polymer Science.Polymer Physics》1992,30(7):717-725
A theoretical model, which takes proper account of the simultaneous uptake of a liquid leachant by a polymer matrix and the consequent release of a bioactive or other solute incorporated therein, is presented and the kinetics of release predicted under various conditions is investigated. This model is shown to be both more rigorous and much more widely applicable than previous attempts to approach the above problem. Furthermore, it can be easily modified or extended, in accordance with the information available about any particular system. It is, therefore, expected that the model introduced here will prove useful as a basis for the design of monolithic controlled-release devices of this type or for the evaluation of the leachability of low-level and medium-level radioactive wastes “immobilized” in polymeric matrices. 相似文献
97.
酸性磷型萃取剂的结构与萃取钴,镍性能关系的研究 总被引:6,自引:1,他引:6
考察了一系列二烷基磷酸酯,烷基膦酸单烷基酯和二烷基膦酸对钴(Ⅱ)、镍(Ⅱ)的萃取性能。应用相关分析法探讨了萃取性能与萃取剂分子中取代基的极性效应和空间效应之间的关系。并依据萃合物立体构型的差异解释了萃取剂结构对萃取钴、镍的不同影响。 相似文献
98.
REUSY-Ex的吸附性能及二次孔结构研究 总被引:1,自引:0,他引:1
应用高真空重量法(分别以苯和正庚烷为吸附质)和低温N2吸附法对REUSY-Ex的吸附性能和二次孔结构进行了研究.结果表明,在水热处理过程中可产生二次孔结构,且二次孔的形成与水热处理的脱铝深度相关.稀HCl浸取REUSY不仅能浸取出位于其二次孔中的非骨架铝(EFAL)碎片,而且还能浸取出位于微孔中的EFAL。29Si MAS NMR的结果显示,稀HCl浸取后,骨架Si(OAl)的谱宽变窄,裂分效果提高,表明其化学环境单一或均匀. 相似文献
99.
A new grafted polymer has been developed by the chemical modification of Amberlite XAD-16 (AXAD-16) polymeric matrix with [(2-dihydroxyarsinoylphenylamino)methyl]phosphonic acid (AXAD-16-AsP). The modified polymer was characterized by a combination of 13C CPMAS and 31P solid-state NMR, Fourier transform-NIR-FIR-Raman spectroscopy, CHNPS elemental analysis, and thermogravimetric analysis (TGA). The distribution studies for the extraction of U(VI), Th(IV), and La(III) from acidic solutions were performed using an AXAD-16-AsP-packed chromatographic column. The influences of various physiochemical parameters on analyte recovery were optimized by both static and dynamic methods. Accordingly, even under high acidities (>4 M), good distribution ratio (D) values (102–104) were achieved for all the analytes. Metal ion desorption was effective using 1 mol L–1 (NH4)2CO3. From kinetic studies, a time duration of <15 min was sufficient for complete metal ion saturation of the resin phase. The maximum metal sorption capacities were found to be 0.25, 0.13, and 1.49 mmol g–1 for U(VI); 0.47, 0.39, and 1.40 mmol g–1 for Th(IV); and 1.44, 1.48, and 1.12 mmol g–1 for La(III), in the presence of 2 mol L–1 HNO3, 2 mol L–1 HCl, and under pH conditions, respectively. The analyte selectivity of the grafted polymer was tested in terms of interfering species tolerance studies. The system showed an enrichment factor of 365, 300, and 270 for U(VI), Th(IV), and La(III), and the limit of analyte detection was in the range of 18–23 ng mL–1. The practical applicability of the polymer was tested with synthetic nuclear spent fuel and seawater mixtures, natural water, and geological samples. The RSD of the total analytical procedure was within 4.9%, thus confirming the reliability of the developed method. 相似文献
100.
Jan-Christoph Panitz Friederike Geiger 《Journal of Sol-Gel Science and Technology》1998,13(1-3):473-477
The effects of preparation method and precursor composition on the leaching behavior of the anthraquinone dye Solvent Blue 59 incorporated into silica based xerogels have been studied. Xerogels were prepared under acidic conditions from mixtures of 20 mol% of organically modified silicon alkoxides, R–Si(OR)3, in Si(OR)4 (R = methyl or ethyl, R = methyl, vinyl, phenyl). The dye was added at the beginning of the sol-gel reaction. The reaction was carried out by either hydrolysis under acidic conditions or acidolysis by formic acid. The dye incorporated was leached with refluxing ethanol using a Soxhlet extraction procedure to simulate the long-term stability of the samples prepared. With increasing size of organic substituent (methyl < vinyl < phenyl), the amount of dye leached decreases. Results from nitrogen adsorption experiments show that all samples characterized have about the same average pore diameter, but they differ in total pore volume and BET surface area. With increasing size of the organic residue, the pore volume decreases by an order of magnitude. Therefore, it is concluded that the microstructure of the xerogels prepared determines the retention behavior of dyes incorporated during the sol-gel reaction. 相似文献